The present invention relates to material removing tools in general, and more particularly to improvements in rotary cutters. Still more particularly, the invention relates to rotary cutters of the type wherein a rotor is driven by a shaft and carries a plurality of external material removing bits as well as a plurality of external nozzles serving to direct sprays of a fluid medium (normally water) against the mine face and/or against the bits.
Longwall drums and continuous miner cutter drums often include water sprays built into them. One purpose of the water sprays is for control of airborne dust generated by the cutting action of the bits. This purpose is usually performed by a spray located in front of each bit. A second purpose is to avoid methane ignition due to the friction of the bit striking rock. This is usually performed by a spray located high on the rear of the bit holder, spraying on the back of the bit and the coal or rock face where the bit has just passed through.
The spray located in front of each bit has usually been mounted directly on the drum scroll, between the bit holders. This requires drilling holes down into the drum""s water passages, and welding on spray housings into which fit the spray nozzles themselves. This is expensive and difficult to weld due to limited accessibility. The number of bits on the drum must sometimes be compromised to provide space for the drum-mounted water sprays.
One of the objects of the invention is to provide a water spray for controlling airborne dust that does not require added space between the bit holders.
Another of the objects of the invention is to provide a water spray for controlling airborne dust that does not require drilling additional holes into the water passageways in the drum.
This invention provides a bit holder already having an integral water passage for a frictional ignition control spray, with a dust control spray by mounting a spray on the rear of each bit holder, thus utilizing water from the bit holder""s integral water passage to spray on the front of the bit of the next bit holder behind it.
More particularly, this invention provides an assembly for mounting a cutter bit on a driven mechanism, the assembly comprising a bit having a bit tip, a bit sleeve including a holding portion adapted to receive the bit, a bore through the holding portion, and a bit holder. The assembly further includes a mounting base having a forward portion and a mounting base rear portion having an internal water passageway in communication with an upper opening for receiving an ignition control unit. The assembly further includes a rear surface having a spray nozzle cavity in the rear surface and open in a rearward direction. The spray nozzle cavity has an internal spray nozzle cavity water passageway in communication with the mounting base rear portion internal water passageway. The assembly further includes a dust reduction unit including a spray nozzle comprising a base received in the spray nozzle cavity, the base having a spray nozzle base water passageway through the spray nozzle base and in communication with the spray nozzle receptacle water passageway. The dust reduction unit further includes a spray orifice in communication with the spray nozzle base water passageway, and means for connecting the spray nozzle to the mounting base rear portion.
This invention provides a significant reduction in cost, when compared to other airborne dust control sprays. The necessary machining is much less expensive on a small bit holder than on a large drum. Further, the bit holders are already machined on computer numerical controlled (CNC) equipment, so the additional machining can be done by the CNC equipment with little added cost. The spray also has the ability to be aimed properly at an adjacent bit with a simple alignment jig, and fixed in that position by welding or clamping. Further, mounting the bit nozzle behind the bit holder reduces the amount of mined material contact with the spray nozzle, thereby increasing the spray""s service life.